[jira] [Created] (IGNITE-24323) Calcite engine. Query execution inside UDF leads to deadlock

["Aleksey Plekhanov (Jira)" <ji...@apache.org>]

Aleksey Plekhanov created IGNITE-24323:
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             Summary: Calcite engine. Query execution inside UDF leads to deadlock
                 Key: IGNITE-24323
                 URL: https://issues.apache.org/jira/browse/IGNITE-24323
             Project: Ignite
          Issue Type: Bug
            Reporter: Aleksey Plekhanov
            Assignee: Aleksey Plekhanov


We have striped executor to execute query tasks. Thread for query/fragment on each node is fixed and defined by hash of query ID and fragment ID. If user created user defined function and try to execute some query inside it, it can lead to deadlock, since task execution thread blocked by new synchronous query execution request and the new query can be assigned to the same thread.
For H2-based SQL engine threads are no binded to the query and there is no such problem.
For Calcite-based SQL engine we use non thread safe datastructures in tasks. 
To workaround this problem we can use regular IgniteThreadPoolExecutor, but need to ensure that there are no tasks concurrently executing for the same query/fragment.
Also, perhaps this approach can affect performance and should be enabled by some property explicitly only for users that require this mode. 
  



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